add comments

1 files changed, 11 insertions, 9 deletions

diff --git a/Advent-of-Code-2022/aoc-5/main.c b/Advent-of-Code-2022/aoc-5/main.c
index 409cf6b..579e33a 100644
--- a/Advent-of-Code-2022/aoc-5/main.c
+++ b/Advent-of-Code-2022/aoc-5/main.c
@@ -2,7 +2,7 @@
 #include <stdlib.h>
 #include <string.h>
 
-#if 0
+#if 1
   #define transfer transfer_part1
 #else
   #define transfer transfer_part2
@@ -21,14 +21,14 @@
 typedef struct crate crate;
 crate *create_crate(char data);
 void push(crate *c, int i);
-crate *add(crate *c, crate *last, int i);
+crate *add(crate *c, crate *last, int i); // pushes an element to bottom of a given stack
 crate *pop(int i);
 void transfer_part1(int from, int to, int n);
 void transfer_part2(int from, int to, int n);
 void free_crates(crate *c);
 void print_crate(char *format, crate *c);
 
-crate *top[COLUMNS+1] = {0};
+crate *top[COLUMNS+1] = {0}; // +1 for part 2
 
 void parse()
 {
@@ -40,11 +40,13 @@ void parse()
 
     char line[256] = {0};
     crate *last[COLUMNS] = {0};
-    while(fgets(line, sizeof(line), fp) != NULL && line[0] != '\n')
+    while(fgets(line, sizeof(line), fp) != NULL)
     {
+        if(line[0] == '\n') break; // the table has ended
+
         for(int i = 0; i < COLUMNS; i++) {
             char ch = line[(i*4)+1];
-            if(ch >= 65 && ch <= 90) {
+            if(ch >= 'A' && ch <= 'Z') {
                 last[i] = add(create_crate(ch), last[i], i);
             }
         }
@@ -52,6 +54,8 @@ void parse()
 
     while(fgets(line, sizeof(line), fp) != NULL)
     {
+        // we need to call strtok multiple times
+        // to get the right token (integer)
         strtok(line, " ");
         int n = STRINT(" ");
         int from = STRINT(" ");
@@ -126,10 +130,8 @@ void transfer_part1(int from, int to, int n)
 
 void transfer_part2(int from, int to, int n)
 {
-    for(int i = 0; i < n; i++)
-        push(pop(from), COLUMNS);
-    for(int i = 0; i < n; i++)
-        push(pop(COLUMNS), to);
+    transfer_part1(from, COLUMNS, n);
+    transfer_part1(COLUMNS, to, n);
 }
 
 void free_crates(crate *c)